VARACTOR Russian patent published in 1997 - IPC

FIELD: semiconductor devices with voltage-controlled reactance. SUBSTANCE: reactor has working region of uniformly doped resistive-contact semiconductor whereon p-n junction to other contact is formed. Working region is made in the form of truncated triangular prism with base sides L₁, L₂, and D. Formed on side faces of working region with sides L₁ and L₂ are p-n junctions or schottky barriers with common contact and on face with side D, resistive contact. Varactor capacitance C due to back bias U in the range of back biases U_min≅ U ≅ U_max satisfies condition , where S₁ and S₂ are geometric areas of faces with sides L₁ and L₂, respectively; R(U) is spatial charge region thickness in semiconductor at back bias U; ε_o= 8,85•10^-2 F/m; ε is relative dielectric constant of semiconductor. Dope concentration in working region and its geometry are chosen so that increasing back bias due to overlapping of spatial charge region from opposing faces causes variation in effective areas of plates S₁(U) and S₂(U); desired variation mechanism S(U) is ensured either by adequate selection of face height as function of distance H f(H) measured from point of intersection of sides L₁ and L₂ with side D along L₁ and L₂ or, in case of given f(h), or by selection of distance between L₁ and L₂ as function of H; size of side D satisfies condition 2R(U_br)≥D≥2R(O), where U_пр is breakdown voltage. Working region may be doped nonuniformly. One of varactor faces with sides L₁ and L₂ is doped-conductor-to-insulating-substrate interface. EFFECT: facilitated control of varactor reactance. 3 cl, 2 dwg